It is well known in the automotive industry to provide a vehicle seat having an air bag mounted on the outboard side of the seat back to provide side impact restraint of a seated occupant. The air bag may include a thorax portion that inflates forwardly of the occupant torso, a head portion that inflates more upwardly and forwardly to restrain the occupant head, and a pelvis portion that inflates more downwardly and forwardly to restrain the occupant pelvis. The air bag is folded up and stored within an air bag housing that is mounted on the seat back. In some cases a plastic door conceals the folded up air bag and then the door opens to permit the deployment of the air bag forwardly and downwardly. However, it is generally considered to be more aesthetically acceptable to hide the air bag assembly within the seat back beneath the traditional seat cover and to provide the seat trim cover with separable seams that can break apart to permit the air bag to deploy forwardly and downwardly.
It would be desirable to provide an improved method for sewing the seat cover to form a continuous C-shaped separable seam and air bag deployment chute.